rkhachatryan commented on a change in pull request #14799: URL: https://github.com/apache/flink/pull/14799#discussion_r567014439
########## File path: flink-runtime/src/main/java/org/apache/flink/runtime/state/proxy/ProxyKeyedStateBackend.java ########## @@ -0,0 +1,306 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.flink.runtime.state.proxy; + +import org.apache.flink.api.common.state.AggregatingStateDescriptor; +import org.apache.flink.api.common.state.ListStateDescriptor; +import org.apache.flink.api.common.state.MapStateDescriptor; +import org.apache.flink.api.common.state.ReducingStateDescriptor; +import org.apache.flink.api.common.state.State; +import org.apache.flink.api.common.state.StateDescriptor; +import org.apache.flink.api.common.state.ValueStateDescriptor; +import org.apache.flink.api.common.typeutils.TypeSerializer; +import org.apache.flink.api.java.tuple.Tuple2; +import org.apache.flink.runtime.checkpoint.CheckpointOptions; +import org.apache.flink.runtime.state.AbstractKeyedStateBackend; +import org.apache.flink.runtime.state.CheckpointStreamFactory; +import org.apache.flink.runtime.state.KeyGroupedInternalPriorityQueue; +import org.apache.flink.runtime.state.Keyed; +import org.apache.flink.runtime.state.KeyedStateFunction; +import org.apache.flink.runtime.state.KeyedStateHandle; +import org.apache.flink.runtime.state.PriorityComparable; +import org.apache.flink.runtime.state.SnapshotResult; +import org.apache.flink.runtime.state.StateSnapshotTransformer; +import org.apache.flink.runtime.state.heap.HeapKeyedStateBackend; +import org.apache.flink.runtime.state.heap.HeapPriorityQueueElement; +import org.apache.flink.runtime.state.internal.InternalKvState; +import org.apache.flink.util.FlinkRuntimeException; +import org.apache.flink.util.IOUtils; + +import javax.annotation.Nonnull; + +import java.util.List; +import java.util.Map; +import java.util.concurrent.RunnableFuture; +import java.util.stream.Collectors; +import java.util.stream.Stream; + +/** */ +public class ProxyKeyedStateBackend<K> extends AbstractKeyedStateBackend<K> { + // wrapped keyed state backend, either HeapKeyedStateBackend or RocksDBKeyedStateBackend + AbstractKeyedStateBackend<K> keyedStateBackend; + + private static final Map<Class<? extends StateDescriptor>, StateFactory> STATE_FACTORIES = + Stream.of( + Tuple2.of( + ValueStateDescriptor.class, + (StateFactory) ProxyValueState::create), + Tuple2.of( + ListStateDescriptor.class, + (StateFactory) ProxyListState::create), + Tuple2.of( + ReducingStateDescriptor.class, + (StateFactory) ProxyReducingState::create), + Tuple2.of( + AggregatingStateDescriptor.class, + (StateFactory) ProxyAggregatingState::create), + Tuple2.of( + MapStateDescriptor.class, (StateFactory) ProxyMapState::create)) + .collect(Collectors.toMap(t -> t.f0, t -> t.f1)); + + public ProxyKeyedStateBackend(AbstractKeyedStateBackend<K> keyedStateBackend) { + super( + keyedStateBackend.kvStateRegistry, + keyedStateBackend.keySerializer, + keyedStateBackend.userCodeClassLoader, + keyedStateBackend.executionConfig, + keyedStateBackend.ttlTimeProvider, + keyedStateBackend.cancelStreamRegistry, + keyedStateBackend.keyGroupCompressionDecorator, + keyedStateBackend.keyContext); + this.keyedStateBackend = keyedStateBackend; Review comment: In the end, we end up with 4 backends: ``` Proxy extends Abstract (has it's own fields AND refers to passed fields) Proxied extends Abstract (has it's own fields AND refers to passed fields) ``` Right? I see the following issues with this: 1. Double caching and lookup in `keyValueStatesByName` 2. Error-prone: 4 backend classes refer to the same `kvStateRegistry`, `keySerializer` etc. making it easy to either call some method twice or not call it for a wrapped backend (e.g. `setCurrentKey` isn't called for the wrapped backend) 3. To me this hierarchy is very confusing ~Why not refactor this in some way or another? Can `AbstractKeyedStateBackend` be also a proxy (i.e. replace inheritance with delegation)?~ edit: I see `keyValueStatesByName` is duplicated but one instance isn't actually used. This moves the weight from (1) to (3) :) Why `ProxyKeyedStateBackend` can't implement `CheckpointableKeyedStateBackend` directly? All it has to override is `getPartitionedState`, everything else should be delegated? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
